Electric call



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D. H. RICE. V ELBOTRIG CALL. No. 307,494. Patented Nov. 4, 1884.

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ELBGTRIG GALL.' No. 307,494. Patented N0v.'4, 1884.

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DAVID HALL RICE, OF LOWELL, MASSACHUSETTS, ASSIGNOR TO THE CUR- Rl'ERTELEPHONE BELL COMPANY, OF MASSACHUSETTS.

ELECTRIC CALL.

SPECIFICATION forming part of Letters Patent No. 307,494, datedNovember. 4, 1884:.

Application filed November 16, 1581. (No model.)

To all whom it may concern.-

Be it known that I, DAVID HALL Bron, of Lowell, in the county ofMiddlesex and State of Massachusetts, have made a new and use- 5 fulImprovement in Electric Calls, of which the following is aspecification, .l My invention relates to the system of callin g devicesinvented by Carl Reinhold Maron, and shown in his German Patent No.1,944, dated December 5, A. D. 1877, and also invented and patented toJacob B. Currier, of Lowell, Massachusetts, in Patent No. 246,374, datedAugust 30, 1881.

It consists in applying to such a system of I electric calls anautomatic calling device operated by the electric current as hereinafterdescribed, so that by the more pressure on a key or change of a switchthe calling device is set in operation, and in turn sets in operationthe bell at the desired station, and con tinues to operate the samewhile the key is pressed or the switch remains so changed. In thedevices of Maron and Currier they employa vibrating springcircuit-breaker set in motion by the hand to make and break the circuitin the time required to ring the desired bell at any distant station.This spring only vibrates for a limited period of time, and must then beset in motion again, and the more freo quentl y as the circuitbreakingspring is shortened. Practically the use of a spring bell-hammervibrating above two thousand times per minute is debarred by itsstructure, because its vibrating spring circuitbrcaker 3 5 becomes soshort as to vibrate too short a time and require too frequent putting inmotion again at these high speeds. Even as the limit indicated isapproached this is the case. It must be understood that a vibratingcircuit- 4:) breaker such as they use cannot be set going a second timewhile the bell-hammer is striking and effectively continue its blows,because it usually catches the hammer going in the op posite directionfrom the pull of the electric 4 5 current which brings the hammer to astate of rest, and is detrimental instead of advantageous. On the otherhand,bells with their hammers Vibrating from one thousand to threethousand times per minute are the best to use in practice, because theirhammers, being provided with shorter or stiffer springs, are lessaffected by the vibrating electric current used to ring bells nearest tothem in vibration of hammer, and they give an alarm which can be heardmuch farther in proportion to the in crease in rapidity of stroke.Thesebells can, therefore, be set much nearer' together in difference oflength of spring-hammer, and the relative distance of their hammersvaries less from their magnets, to give them an effective repetition ofblows on the bell, thus causing them, with the same battery-power, toring nearer alike. My improvement not only enables me to make use ofthese bells in the most efficient manner, but also is ofadvantage uponany bell of this character, saving time and trouble in the telephoneolfice, and giving greater certainty of calling the station wanted.

In the drawings, Figure 1 shows a circuit provided with my improvement.Fig. 2 represents a top view of the switch and its mode of connectionwith the several circuits which it is used with, as hereinafter stated.Fig. 3 represents a side view of the switch.

This switch is so well known that no detailed description of it isnecessary. It is placed at S in the circuits, and by swinging the metalswitch A over from the contact point a of one circuit to the contact aof another upon its pivot b the circuit L is grounded through L or L atpleasure.

A is the thumbbutton. b is the metal pivot on which the switch A turns.a a are metal contact-points of switch, to which lines L L areconnected. C is the wooden baseboard of the switch. A is the centraloffice.

A A are two subscribers stations on the circuit L, provided with magnetsM, hammers H H, and bells B of the Currier construction, which need notbe further described than to say that they are adjusted to ring atdifferent known rates of vibration by a broken or vibrative current sentfrom the central office in the manner described in said Currier patent.G G are ground-connections of the circuit. At S in the central officeaswitch of any Well-known construction is used to shunt in either theline L,on which the magneto dropbuttons and telephone may be placed inany usual and wellknown manner, or the line L, on which is the groundedcalling mechanism and battery X, at pleasure. WVhen the switch Sconnects one of these lines, the other is disconnected from-the maincircuit. From the batteryI run the line L byshortbranches, as shown, tothe screws T T, which are in electrical contact at their points with thesprings of the vibrating armatures V V. It will be observed that in thisarrangement of the contact-points of the screws T T with the elasticsprings of the armatures V V, these points are so placed that thearmature moves while its spring is in contact with it around the screwcontact-point as a center, by which means the synchronosity of its rateof vibratlon is preserved within practi cablelimits, and, what is moreimportant, their contact is maintalned when the magnet pulls thearmature toward it, in the first instance, long enough to give themagnet strength to start the armature in vibration as well by theamplitude of the first movement-given to it as by the certainty ofbreaking the circuit before the tension of the spring has neutralizedthe pull of the magnet and thus prevented the circuit being broken. Itis upon these two effects of amplitude of the initial vibration of thearmature and certainty of breaking the circuit before such initialvibration ceases that the ability to practically use the main electriccurrent to set in motion the circuit-breaker depends.

As I have before stated, while the use of the point of the screw T as acenter of vibration accomplishes this it accomplishes the third equallyimportant result of allowing the synchronosity of vibration of thearmature to be maintained, I thus dispense with all other mechanism-suchas hand-levers, local circuits, or clock-workto operate the armatures VV, as described. These armatures are set in posts 0 a at the ends oftheir elastic parts. The posts 0 c are connected by a wire to one poleof the magnets M M, while the other pole is connected to the contactpoints E E of the keys K K. These keys have their axes connected totheline L, and are made of metal. The armature V is adjusted to vibrate inthe same time as the hammer H of the bell at station A, and the armatureV is adjusted in like manner to the time of the hammer H at station A.

The operation is as follows: Suppose it be desired to ring the bell atstation A. The

key K is depressed'into contact with E. The first impulse of theelectric current through its magnet depresses the armature V and breaksthe circuit at the point of screw T, releasing the armature, when itflies back, makes contact at the point of T, and is again drawn towardthe magnet, repeating the operation as long as key K is depressed. Thebroken electric current thus made, being in the time of the hammer H,sets it to vibrating, and it continues to strike the bell as long as thecurrent continues by pressing on key K. By pressing key K down to itscontact-point E, the bell at station A is lung in like manner. Thestations A A may be any distance apart on the circuit, and anyconvenient number of stations may be placed on it by providing acorresponding number of automatic callers having armatures synchronouslyadjusted to the vibration of the different bell-hammers.

Instead of a complete make and break, the armatures V V may only vibratesufliciently to vary the pressure on their screws T, so as to createundulatory currents, if desired.

Instead of keys K K, pins may be used, or any other we1l-knowndevices,to complete the circuit. The hammers or strikers H H may be madeto close a local circuit, or set off an alarm, or switch the electriccurrent upon a branch circuit in the manner described in the Patent No.240,010, granted to Currier and Rice, April 12, 1881. In short, myautomatic circuit-breakers may be used in a variety of ways to ring anydesired bell at different stations by the broken or vibratory naturethey impart to the current from its own action in the same manner as theinventions of Maron and Currier, referred to.

What I claim as new and of my invention 1. In combination with astriker, H, and its magnet adapted to be operated by a broken orundulatory current sent from adistant station, an automatic circuitbreaker operated by the electric current, substantially as described.

2. In combination with the circuit L and keys K K, the circuit-breakersoperated by the electric current and connected to the same battery andground, substantially as described.

DAVID HALL RICE.

Witnesses:

GEQJH. WHITE, N. P. OOKINGTON.

